Error checking in format-network-address

Error checking in format-network-address

[Juanma Barranquero]

The docstring for `format-network-address' says: "Returns nil if
format of address is invalid." However, the function does not do much
error checking, other than rejecting nil arguments and vectors not of
the right size.

It blindingly accepts absurd IP addresses, though:

ELISP> (format-network-address [0 256 -256 100000 -7])
"0.256.-256.100000:-7"
ELISP> (format-network-address [1 2 3 4 5 6 -777777 88888888])
"1:2:3:4:5:6:1ff421cf:54c5638"

I suggest the attached patch, which forces the function to return nil
for such pathological cases.

The function accepts also cons pairs and strings with no almost no
error checking whatsoever:

ELISP> (format-network-address "any:stuff")
"any:stuff"
ELISP> (format-network-address (cons -100 'stuff))
"<Family -100>"

but as those format are not documented I suppose they're OK.

             Juanma



Index: src/process.c
===================================================================
RCS file: /cvsroot/emacs/emacs/src/process.c,v
retrieving revision 1.508
diff -u -2 -r1.508 process.c
--- src/process.c	27 Mar 2007 15:19:33 -0000	1.508
+++ src/process.c	27 Mar 2007 15:38:12 -0000
@@ -1296,5 +1296,18 @@

       for (i = 0; i < nargs; i++)
-	args[i+1] = p->contents[i];
+	{
+	  int element = XINT (p->contents[i]);
+
+	  if (element < 0 || element > 65535)
+	    return Qnil;
+
+	  if ((nargs < 8)          /* IPv4 */
+	      && (i < 4)           /* host, not port */
+	      && (element > 255))
+	    return Qnil;
+
+	  args[i+1] = p->contents[i];
+	}
+
       return Fformat (nargs+1, args);
     }

Re: Error checking in format-network-address

[Andreas Schwab]

"Juanma Barranquero" <lekktu@gmail.com> writes:

> Index: src/process.c
> ===================================================================
> RCS file: /cvsroot/emacs/emacs/src/process.c,v
> retrieving revision 1.508
> diff -u -2 -r1.508 process.c
> --- src/process.c	27 Mar 2007 15:19:33 -0000	1.508
> +++ src/process.c	27 Mar 2007 15:38:12 -0000
> @@ -1296,5 +1296,18 @@
>
>       for (i = 0; i < nargs; i++)
> -	args[i+1] = p->contents[i];
> +	{
> +	  int element = XINT (p->contents[i]);

Better use EMACS_INT here.

Andreas.

-- 
Andreas Schwab, SuSE Labs, schwab@suse.de
SuSE Linux Products GmbH, Maxfeldstraße 5, 90409 Nürnberg, Germany
PGP key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."

Re: Error checking in format-network-address

[Juanma Barranquero]

On 3/27/07, Andreas Schwab <schwab@suse.de> wrote:

> Better use EMACS_INT here.

You're right. Thanks!

             Juanma